1. Field of the Invention
The present invention relates to the field pulse width keying. In particular, the present invention relate to the field of determining pulse related characteristics of pulse width keyed signals.
2. Related Art
Pulse width keying uses the length of a pulse over a time period for bit representation. In some modulation schemes, for example, a bit “0” is represented as a 1.0 millisecond (ms) pulse followed by 0.5 ms blanking time. In these schemes, a bit “1” might be represented as a 0.5 ms pulse followed by 1.0 ms blanking time.
In practice, pulse width keyed signals are used in a variety of applications. Included in these applications is the field of modern radar and radar receivers. Radars use pulse width keyed signals, for example, to determine target range, speed, and angle data. Radar receivers, such as radar warning receivers used in military applications, can discriminate between different radars, and different types of radars, on the basis of the pulse related characteristics of their respective pulse keyed signals.
A major shortcoming of using pulse width keyed signals, however, is the ability of the receiving system to accurately measure pulse data in noisy environments. Many conventional receiving systems, for example, rely purely upon envelope and amplitude threshold detection techniques to measure characteristics, such as pulse widths. In noisy environments, however, it becomes difficult to distinguish actual pulse related data from noise, using the conventional threshold detection techniques.
What is needed, therefore, is a more robust technique to detect and measure pulse related characteristics, such as pulse widths, associated with pulse width keyed signals.